The recent progress of an organic light emitting device is significant, and the device suggests its potential to find use in a wide variety of applications because of the following reasons. The device shows a high luminance at a low applied voltage. In addition, the device has a variety of emission wavelengths. Furthermore, the device can be a thin, light-weight light emitting device with high-speed responsiveness.
However, at present, an optical output with additionally high luminance, or additionally high conversion efficiency has been needed. In addition, the organic light emitting device still has many problems in terms of durability. For example, the device changes over time owing to long-term use, and deteriorates owing to an atmospheric gas containing oxygen, humidity, or the like. Further, in the case where it is assumed that the device is applied to, for example, a full-color display, the device must emit blue light, green light, and red light each having good color purity. However, problems concerning the color purity of each of the blue light, the green light, and the red light have not been sufficiently solved yet.
In addition, research has been conducted on a large number of aromatic compounds and condensed polycyclic aromatic compounds as fluorescent organic compounds each of which is used in, for example, an electron transport layer or a light emitting layer. However, it is hard to say that a compound capable of sufficiently satisfying emission luminance or durability has been obtained.
Japanese Patent Application Laid-Open No. 2004-43349, International Publication No. 99/54385, and Japanese Patent Application Laid-Open No. 2003-229273 each disclose the application of a fluorene compound to an organic EL. In addition, Journal of Fluorescence, Vol. 5, No. 3, 295 (1995) reports a fluorene compound to be applied to a laser dye.